Invalids and bedridden people, whose opportunities for leg exercise are severly limited, are subject to an increased risk of thrombophlebitis which is defined as an inflammation of a vein with the formation of a thrombus (blood clot). Thrombophlebitis can eventially lead to pulmonary embolism
The most common location for the formation of such clots is found in the deep veins of the legs where pooling and stagnation of blood occurs due to poor circulation as a result of little or no leg exercise. Exercising of the leg muscles, especially the calf muscles, facilitates the movement of blood in the deep veins of the leg, thus lessening the risks of blood clot formation.
It has been common practice to massage the legs of invalids and bedridden patients in order to maintain leg muscle tone and circulation, which in turn decreases the risk of thrombophlebitis. However, due to the shortage of nurses and physical therapists, patients may not receive the necessary routine massages or leg exercises.
Apparatuses for massaging or exercising legs have been too cumbersome and/or expensive to be widely available in most hospitals and are especially not readily available to non-hospitalized patients.
Lowth in U.S. Pat. No. 4,159,111 discloses a leg exercising apparatus which is supposed to approximate a walking motion. The apparatus consists of two solid, one piece, hinged foot pedals connected to each other through a pivotal point. As one pedal is pushed down it forces the other pedal to rise. Since each hinged pedal is a solid unit, without any flexibility, the exerciser's foot does not flex, as in normal walking, unless the heel leaves the foot pedal. Therefore, using the Lowth apparatus the leg muscles, especially the calf muscles, do not contract to the same degree as in walking when there is a flexing of the foot. There is also a second disadvantage associated with the Lowth apparatus in that when the apparatus is used by a patient in the supine position the patient's feet would have a tendency to slip off the pedals.
A second exercising device is disclosed by Wood in U.S. Pat. No. 1,990,970. Here weights are added to a shoe having rigid sole portions. Again the shoe has a solid unitary body providing no flexibility. This arrangement may be useful for people in good physical condition, who want to use the apparatus for strengthening leg muscles. The Wood apparatus, however, is not conducive for use by invalids or bedridden patients who require an apparatus for contracting and stretching leg muscles as opposed to an apparatus which is intended to build muscle mass.
Although both apparatuses are supposedly designed to exercise leg muscles, neither apparatus incorporates features, other than movement of the foot about the ankle joint, to exercise calf muscles. As stated above, however, in order to facilitate the pumping of the blood from the deep veins, the calf muscles must be contracted and extended. For the non-invalid such exercise of calf muscles is provided by walking where the foot is flexed about both the ankle joint and about the ball of the foot. For the reasons advanced above, neither of the above described apparatuses provide an efficient leg exerciser for preventing thrombophlebitis in invalids or bedridden patients.